This invention relates to vinyl chloride-grafted ethylene copolymer and a process for producing same. More particularly, it relates to vinyl chloride-grafted ethylene-acrylic or-methacrylic ester-maleic anhydride copolymer and a process for producing same.
Polyolefins represented by polyethylene and polypropylene are economically produced in a large amount and widly used, since they have superior mechanical strength, electric characteristics and processability and are inexpensive and useful for general-purpose. However, difficulty is encounted when lamination is made between polyolefins and other materials to prepare composite articles, since polyolefins are so nonpolar that they are poor in adhesiveness.
For improvement of adhesiveness of polyolefins, there is a method where ethylene is copolymerized with a copolymerizable and adhesiveness-impartable component such as glycidyl methacrylate or maleic anhydride (cf. Japanese Patent Examined Publication No. 27517/71, etc.). Furthermore, there are the methods where unsaturated carboxylic acid or its anhydride such as acrylic acid or maleic anhydride is grafted on polyolefins such as polyethylene to introduce a polar group, thereby imparting adhesiveness to metals, glasses or polar high molecular materials such as nylon (polyamide) (cf. Japanese Patent Examined Publication Nos. 18392/62 and 32654/77). Although these copolymers are relatively good in adhesiveness to metals, glasses or for example, polyamides, they have substantially no adhesiveness to non-rigid vinyl chloride resin which is one of the most widely used high molecular materials.
There are also proposed many methods of grafting vinyl chloride on ethylene copolymers such as ethylene-vinyl acetate copolymer and ethylenemethyl methacrylate copolymer (cf. Japanese Patent Examined Publication Nos. 27876/64 and 14229/68) and the products are utilized as wire coating materials, an impact strength modifier for vinyl chloride polymers, etc. These vinyl chloride-grafted ethylene copolymers have small adhesiveness to polymers of relatively high polarity such as polyamides and polyesters. For example, waterproof fabrics prepared by lamination of non-rigid vinyl chloride resin and a base fabric made of such as polyamide or polyester, using the vinyl chloride-grafted ethylene copolymer as an adhesive, are inferior in adhesion and have no sufficient strength.